The charts below are from Patrick O'Shaughnessy's research on momentum. First, there are periods of poor performance. You cannot get away from it. It looks like these crashes come after a big market downturn, but there is limited information to classify these events.
The main job of the risk management rules is to mitigate the crash risk inherent to these strategies. No investor or manager should think about momentum strategies without a risk management exit strategy. Risk management has been more important over the last five year not because of some new view of finance, but because it is critical to save managers when the strategy is not working. Momentum has been good but currently it is important to look beyond this approach.